/* The gray code is a binary numeral system where two successive values differ in only one bit.
 *
 * Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.
 *
 * For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:
 *
 * 00 - 0
 * 01 - 1
 * 11 - 3
 * 10 - 2
 * Note:
 * For a given n, a gray code sequence is not uniquely defined.
 *
 * For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.
 *
 * For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.
 */

class Solution {

public:
	vector<int> grayCode(int n) {
		int range = 1 << n;
		int i;
		vector<int> result;
		for(i=0;i<range;i++){
			result.push_back(i^(i/2));
		}
		return result;

	}

};
